Reference to FIG. 1 shows a single jet prop engine powered high wing, Canard-type aircraft to which the invention has particular application. The aircraft indicated generally at 10, is driven by a prop jet engine supported by the fuselage 12 at the rear end 12a thereof. The aircraft is of the high wing type. Specifically a high main wing 14 is mounted to the fuselage 12 and spans across the top of the same. The aircraft 10 is not equipped with a conventional horizontal stabilizer. Instead a pair of canards 16 which, like the main wing 14 comprise lifting surfaces of air flow configuration add to the lift imparted by the main wing 14 and extend horizontally outwardly from the aircraft fuselage near the nose thereof and to respective sides. The aircraft lacks a conventional vertical tail. However, the main wing 14 is provided at opposite ends, with upwardly and downwardly inclined winglets 18, 18' integrated to the tips of the main wing 14. The jet prop engine drives a propeller 22 to push the aircraft with portion 12a of the fuselage acting as the engine housing for the engine.
Such high wing, canard aircraft lacking the downthrust producing conventional horizontal stabilizer, are highly fuel efficient and designed for long distance flight. As a result, they are capable of carrying large quantities of fuel which must be distributed throughout the aircraft. However, fuel stored in multiple tanks has historically been a problem from time to time, as pilots forget to switch tanks or a valve fails to respond to control commands. As a consequence, a number of incidents and accidents have occurred. As may be appreciated, the fore and aft weight and balance and, therefore, attitude of the aircraft is critical to the flight capability of the aircraft, particularly with respect to the canards 16. This safety issue is addressed effectively by this invention.
To provide a fuel system for long distance flights, such aircraft requires a number of fuel tanks to be mounted both along the fuselage and the main wings. As a result, fuel is distributed over a wide distance fore and aft. With the fuel distributed over a wide distance fore and aft, with the fuel distributed over such a wide distance, any tendency of the fuel to concentrate at one position or the other within the aircraft fuel system can be equally disturbing to flight control and under severe conditions render the aircraft incapable of flight.
It is therefore a primary object of the present invention to provide an improved fuel system for a canard aircraft in which a number of fuel tanks are mounted in fore and aft alignment along the fuselage and in both inboard high main wings and are integrated in a fuel distribution system to a tank within the center high main wing section, which utilizes a single collector tank feeding to the engine, in which the tanks are self-levelling, to minimize center of gravity shifts during flight and in which virtually all the fuel is transferred to the collector tank during the course of flight.
It is a further object of the invention to provide a fuel system utilizing gravity effect for transferring fuel from individual tanks to a common collector tank which utilizes simple flapper check valves for preventing fuel, once reaching the collector tank, from leaving that tank and for isolating each tank from the others to prevent large fuel excursions during extreme flight maneuvers.